Pericarpium citri reticulatae flavone microcapsule as well as preparation method and application thereof

Abstract

The invention discloses a pericarpium citri reticulatae flavone microcapsule as well as a preparation method and application thereof. The method comprises the following steps: extracting dried orange peel powder by taking an ethanol solution as an extraction solvent and adopting a subcritical extraction method, and carrying out vacuum concentration and freeze drying on the obtained extract to obtain dried orange peel flavone freeze-dried powder; dissolving the dried tangerine peel flavone freeze-dried powder with water to obtain a core material solution; maltodextrin and vegetable protein are dissolved in water, and a wall material solution is obtained; and uniformly mixing the core material solution and the wall material solution, and performing vacuum freeze drying to obtain the pericarpium citri reticulatae flavone microcapsule. The microcapsule has the advantages of high embedding rate and strong storage stability; and the microcapsule wall material is natural and non-toxic and can be applied as a food additive.

Description

Technical Field

[0001] The invention belongs to the technical field of microcapsules and preparation thereof, and particularly relates to tangerine peel flavonoids microcapsules and a preparation method and application thereof. Background Art

[0002] Tangerine peel, derived from the mature peel of the citrus plant and its cultivated varieties of the Rutaceae family, is one of my country's traditional Chinese herbal medicines. It tastes bitter and pungent, is warm in nature, and belongs to the lung and spleen meridians. It has the effects of promoting qi and strengthening the spleen, harmonizing the stomach and stopping vomiting, and drying dampness and resolving phlegm. Tangerine peel is made by picking ripe fruits, peeling the peel, and drying it in the sun or at low temperature. The air-drying time is usually more than one year. Flavonoid compounds in tangerine peel are one of its important active ingredients, with high medical value, and are also an important component of people's daily diet. This substance can significantly reduce cholesterol levels, prevent the proliferation and apoptosis of human oral squamous cell carcinoma cells, scavenge free radicals and antioxidant capacity, protect the nervous system and cardiovascular damage, and have anti-atherosclerosis and anti-depression functions. It has great application prospects in food, medicine, daily chemicals, etc. However, flavonoid compounds have poor solubility, are sensitive to external environments such as light, temperature, and oxygen, and have poor permeability in the human gastrointestinal tract, which limits their absorption in the human body, reduces the bioavailability of these active ingredients, and seriously limits their applicability and durability.

[0003] Microencapsulation technology is an effective way to solve this problem. It uses polymer wall materials to form micro-embedded materials, so that the active ingredients are protected from the influence of the external environment, and the function of controlled release of components is achieved while improving the stability of the core material. Plant protein has good biocompatibility, biodegradability, amphiphilicity and functional properties, such as water solubility, emulsification and foaming ability. In food applications, it is known that plant protein has lower allergenicity than animal-derived proteins. However, single protein microcapsules will be denatured and changed due to the environment during preparation and application. Maltodextrin is a polysaccharide food raw material, which is extracted from starch-containing raw materials such as corn and rice by enzymatic process. It has the advantages of gelling, thickening and enhancing stability. Plant protein is combined with polysaccharides, and the two interact through non-covalent and covalent interactions to form a complex with specific structure and function. This interaction enhances the thermal stability and pH sensitivity of the microcapsules, thereby improving the encapsulation efficiency. Compared with chemical modification, this method is safer and more environmentally friendly.

[0004] In recent years, the research progress of flavonoids in tangerine peel has mainly focused on the optimization of purification process, structural identification and antioxidant capacity; however, how to improve its storage stability through microencapsulation technology to optimize the practical application of tangerine peel flavonoid functional products is an urgent problem to be solved. However, there is no report on the microencapsulation preparation of tangerine peel flavonoid compounds and its process optimization. Summary of the invention

[0005] The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a method for preparing tangerine peel flavonoids microcapsules.

[0006] Another object of the present invention is to provide tangerine peel flavonoids microcapsules obtained by the above preparation method.

[0007] Another object of the present invention is to provide application of the above-mentioned tangerine peel flavonoids microcapsules.

[0008] The purpose of the present invention is achieved by the following technical solution: A method for preparing tangerine peel flavonoids microcapsules, comprising the following steps:

[0009] (1) Preparation of core material: Using ethanol solution as extraction solvent, extracting tangerine peel powder by subcritical extraction method, concentrating the obtained extract under reduced pressure, and freeze-drying to obtain tangerine peel flavonoid freeze-dried powder; dissolving the tangerine peel flavonoid freeze-dried powder in water to obtain core material solution;

[0010] (2) Preparation of wall material: dissolving maltodextrin and vegetable protein in water to obtain a wall material solution;

[0011] (3) Preparation of tangerine peel flavonoids microcapsules: The core material solution obtained in step (1) and the wall material solution obtained in step (2) are mixed evenly, and vacuum freeze-dried to obtain tangerine peel flavonoids microcapsules.

[0012] The tangerine peel powder described in step (1) is preferably tangerine peel powder that can be obtained by passing through an 80-mesh sieve.

[0013] The consumption of the ethanol solution described in step (1) is preferably calculated by the ratio of 1g tangerine peel powder to 20-30mL ethanol solution.

[0014] The concentration of the ethanol solution in step (1) is preferably 55 to 95% by volume; more preferably 60 to 70% by volume.

[0015] The extraction conditions in step (1) are preferably as follows: the extraction temperature is 120-160° C., and the extraction time is 30-120 min; more preferably as follows: the extraction temperature is 160° C., and the extraction time is 60-120 min.

[0016] The freeze-drying conditions described in step (1) are preferably: pressure 0.5-1.5 Pa, cold trap temperature -60°C.

[0017] The concentration of the core material solution in step (1) is preferably 1 to 10% by mass.

[0018] The vegetable protein described in step (2) is preferably at least one of sunflower seed protein, rapeseed protein isolate, sesame protein isolate, amaranth protein, lupin protein and soy protein isolate.

[0019] Step (2) is preferably as follows: maltodextrin and vegetable protein are dissolved in water respectively, and the obtained maltodextrin solution and vegetable protein solution are mixed to obtain a wall material solution.

[0020] The concentration of the maltodextrin solution is preferably 8-12% by volume, and more preferably 10% by volume.

[0021] The concentration of the vegetable protein solution is preferably 5-15% by mass volume; more preferably 5-10% by mass volume.

[0022] The maltodextrin solution and the plant protein solution are preferably mixed in a mass ratio of 1:9 to 1:9; more preferably in a mass ratio of 1 to 3:1 to 3; most preferably in a mass ratio of 1 to 2:1 to 3.

[0023] When the maltodextrin is dissolved in water, it is preferably heated to promote dissolution; more preferably, it is heated to 50-90° C. and stirred for dissolution.

[0024] When the vegetable protein is dissolved in water, it is preferably heated to promote dissolution; more preferably, it is heated to 50-90°C and stirred for dissolution; and most preferably, it is heated to 50-70°C and stirred for dissolution.

[0025] The concentration of maltodextrin in the wall material solution in step (2) is 2-10%, preferably 4-5%; the concentration of plant protein is 2-10%, preferably 5-6%.

[0026] The core material and the wall material of the tangerine peel flavonoids microcapsules described in step (3) are mixed in a mass ratio of 7.5-10:80-140.

[0027] The mixing conditions in step (3) are preferably as follows: stirring speed 200-900 rpm, stirring time 10-60 min; more preferably as follows: 700-900 rpm, stirring time 30-40 min.

[0028] A tangerine peel flavonoids microcapsule is obtained through the preparation method.

[0029] Application of the above tangerine peel flavonoids microcapsules in the preparation of food additives.

[0030] Compared with the prior art, the present invention has the following advantages and effects:

[0031] (1) The tangerine peel flavonoids extraction method provided by the present invention is a subcritical ethanol extraction method, which has a simple process, does not require an organic solvent, and has a low process cost; the extraction conditions are relatively mild, the tangerine peel flavonoids are not easy to deteriorate and inactivate, and the extraction rate is high, and the effective components are less damaged.

[0032] (2) The microcapsules prepared by the inventive technology have a high embedding rate and strong storage stability; the microcapsule wall material is natural and non-toxic, and the preparation method is simple. The microencapsulated tangerine peel flavonoids can be conveniently added to various foods, such as beverages, cakes, yogurt, etc., and can also be used as a raw material for health foods to increase the added value of the products; tangerine peel flavonoids itself has multiple physiological activities such as antioxidant, anti-inflammatory, and cardiovascular protection. After microencapsulation, these functions can be more effectively exerted, and it can be applied to functional foods and health products. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the standard curve of hesperidin. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0035] The preparation steps of the tangerine peel powder used in the present invention are as follows: placing three-year tangerine peel in an electric constant temperature drying oven at 60° C. and drying to constant weight, grinding and passing through an 80-mesh sieve to obtain the tangerine peel powder.

[0036] The sunflower seed protein used in the present invention is prepared according to the reference "Qin Narisu, Li Hongjie, Li Xuexin, et al. Research on the process of ultrasonic-assisted macroporous resin extraction of light-colored sunflower seed protein [J]. Journal of the Chinese Cereals and Oils Association, 2022, 37(11): 221-226."

[0037] The rapeseed protein isolate used in the present invention is prepared according to the reference “Yao Yijun, Yuan Qiang, Ju Xingrong, et al. Isolation, purification and anti-tumor activity of rapeseed protein hydrolysate [J]. Journal of the Chinese Cereals and Oils Association, 2019, 34(7): 47-53.”

[0038] The sesame protein isolate used in the present invention is prepared according to the reference “Wang Yidan, Sun Ye, Luo Shuizhong. Preparation of sesame protein isolate and stability of its albumin emulsion [J]. Food Research and Development, 2023, 44(15): 76-83.”

[0039] The amaranth protein used in the present invention is prepared according to the reference “Lin Yanru, Zhang Xiaozhi. Research on the extraction process of amaranth leaf protein [J]. Northern Horticulture, 2013, (18): 139-142.”

[0040] The lupin protein used in the present invention is prepared according to the reference "He Shenghua, Wang Yonghui, Deng Qianchun. Physicochemical properties of lupin protein extracted by micellization and alkali dissolution and acid precipitation [J]. Food Science, 2022, 43(8): 36-43."

[0041] Example 1

[0042] A tangerine peel flavonoids microcapsule is prepared by the following steps:

[0043] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0044] (2) Dissolve maltodextrin and sunflower seed protein in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a sunflower seed protein solution with a mass volume concentration of 10% at 50° C. and 70° C., respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0045] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0046] Example 2

[0047] A tangerine peel flavonoids microcapsule is prepared by the following steps:

[0048] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0049] (2) Dissolve maltodextrin and rapeseed protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a rapeseed protein isolate solution with a mass volume concentration of 10% at 50° C. and 55° C., respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0050] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0051] Example 3

[0052] A tangerine peel flavonoids microcapsule is prepared by the following steps:

[0053] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0054] (2) Dissolve maltodextrin and sesame protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a sesame protein isolate solution with a mass volume concentration of 10% at 50° C. and 60° C., respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0055] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0056] Example 4

[0057] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0058] (2) Dissolve maltodextrin and amaranth protein in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and amaranth protein solution with a mass volume concentration of 10% at 50°C and 55°C, respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0059] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0060] Example 5

[0061] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0062] (2) Dissolve maltodextrin and lupin protein in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a lupin protein solution with a mass volume concentration of 10% at 50°C and 70°C, respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0063] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0064] Example 6

[0065] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0066] (2) Dissolve maltodextrin and soy protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a soy protein isolate solution with a mass volume concentration of 10% at 50°C and 65°C, respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0067] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0068] Example 7

[0069] A tangerine peel flavonoids microcapsule is prepared by the following steps:

[0070] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0071] (2) Dissolve maltodextrin and sesame protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a sesame protein isolate solution with a mass volume concentration of 10% at 50° C. and 60° C., respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0072] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) are mixed in a mass ratio of 1:14, stirred at 900 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of −60° C., and a sample temperature of −30° C. to obtain tangerine peel flavonoids microcapsules.

[0073] Example 8

[0074] A tangerine peel flavonoids microcapsule is prepared by the following steps:

[0075] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0076] (2) Dissolve maltodextrin and sesame protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a sesame protein isolate solution with a mass volume concentration of 10% at 50° C. and 60° C., respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0077] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:8, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0078] Example 9

[0079] A tangerine peel flavonoids microcapsule is prepared by the following steps:

[0080] (1) Extraction by subcritical ethanol extraction: Weigh the dried tangerine peel flavonoids powder in a subcritical reactor, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, extract at 160°C for 120 min, and obtain the dried tangerine peel flavonoids extract. All the collected extracts are pooled together, concentrated under reduced pressure, and vacuum freeze-dried for 24 hours under the conditions of pressure 1.0 Pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder is dissolved in distilled water to prepare a solution with a mass (g) volume (mL) concentration of 10% to obtain a core material solution.

[0081] (2) Dissolve maltodextrin and sesame protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a sesame protein isolate solution with a mass volume concentration of 10% at 50°C and 60°C, respectively, and then mix the two in a mass ratio of 2:3, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0082] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample plate, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0083] Comparative Example 1

[0084] A tangerine peel flavonoids microcapsule is prepared by the following steps:

[0085] (1) Extraction by ultrasound-assisted extraction: Weigh tangerine peel flavonoids powder in a beaker, add 60% vol ethanol solution at a solid-liquid ratio of 1:30 g / mL, and ultrasonicate for 30 min at 200 W to obtain tangerine peel flavonoids extract. Filter the extract under reduced pressure and concentrate, and vacuum freeze-dry for 24 h at a pressure of 1.0 pa, a cold trap temperature of -60°C, and a sample temperature of -30°C to obtain tangerine peel flavonoids freeze-dried powder. Dissolve the tangerine peel flavonoids freeze-dried powder in distilled water to prepare a solution with a mass volume concentration of 10% to obtain a core material solution.

[0086] (2) Dissolve maltodextrin and sesame protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a sesame protein isolate solution with a mass volume concentration of 10% at 50° C. and 60° C., respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0087] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0088] Comparative Example 2

[0089] (1) Extraction by ethanol hot reflux method: Weigh the dried tangerine peel flavonoids powder in a round-bottom flask, add 60 vol% ethanol solution according to the solid-liquid ratio of 1:30 g / mL, reflux for 60 min at 70°C to obtain the dried tangerine peel flavonoids extract. The extract was filtered and concentrated under reduced pressure, and vacuum freeze-dried for 24 h under the conditions of pressure 1.0 pa, cold trap temperature -60°C and sample temperature -30°C to obtain the dried tangerine peel flavonoids freeze-dried powder. The dried tangerine peel flavonoids freeze-dried powder was dissolved in distilled water to prepare a solution with a mass volume concentration of 10% to obtain the core material solution.

[0090] (2) Dissolve maltodextrin and sesame protein isolate in distilled water, prepare a maltodextrin solution with a mass volume concentration of 10% and a sesame protein isolate solution with a mass volume concentration of 10% at 50° C. and 60° C., respectively, and then mix the two in a mass ratio of 1:1, stir at 600 rpm for 30 minutes at room temperature to obtain an embedding wall material mixed solution.

[0091] (3) The wall material solution obtained in step (1) and the core material solution obtained in step (2) were mixed in a mass ratio of 1:14, stirred at 700 rpm for 40 min at 25° C., spread on a freeze dryer sample, frozen overnight, and vacuum freeze-dried for 48 hours under the conditions of a pressure of 1.5 Pa, a cold trap temperature of -60° C., and a sample temperature of -30° C. to obtain tangerine peel flavonoids microcapsules.

[0092] Effect Example 1 Determination of microcapsule embedding rate

[0093] (1) Drawing of the standard curve of hesperidin:

[0094] Accurately weigh 0.25 g of hesperidin standard that has been dried to constant weight, add 60% vol ethanol solution to a 50 mL volumetric flask after ultrasonic treatment, and shake well to obtain a 5 mg / mL hesperidin standard solution. Accurately pipette 0.0 mL, 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, and 2.5 mL of the hesperidin standard solution into a 25 mL volumetric flask, and dilute to 25 mL with distilled water; use distilled water as a blank reference, and measure the absorbance at 285 nm to obtain a hesperidin standard curve.

[0095] (2) Determination of total flavonoid content in microcapsules:

[0096] Weigh 0.3 g of tangerine peel flavonoid capsules, add 60% ethanol solution at a volume ratio of 1:60, extract at 200W ultrasonic for 30 min, centrifuge at 3000r / min for 15 min, take 1 mL of supernatant, make the volume to 10 mL, measure its absorbance at 285nm, use hesperidin as the standard, substitute into the hesperidin standard curve to obtain the total flavonoid content of the microcapsules.

[0097] (3) Determination of flavonoid content on the surface of microcapsules:

[0098] Weigh 0.3 g of tangerine peel flavonoid capsules, add anhydrous ethanol at a volume ratio of 1:60, extract at 200W ultrasonically for 30 min, centrifuge at 3000r / min for 15 min, take 1 mL of supernatant, make the volume to 10 mL, measure its absorbance at 285 nm, use hesperidin as the standard, and substitute it into the hesperidin standard curve to obtain the flavonoid content on the surface of the microcapsules.

[0099] (4) The calculation formula of embedding rate is as follows:

[0100] Embedding rate (%) = (1-flavonoid content on the microcapsule surface / total flavonoid content in the microcapsule) × 100%.

[0101] (5) Test results and analysis:

[0102] The results of drawing the standard curve of hesperidin are shown in the attached figure. Figure 1 As shown. From the test results, the linear regression equation between the absorbance value and the hesperidin content is: y = 1.2582x + 0.0105;

[0103] The effects of different composite wall materials on the embedding rate of tangerine peel flavonoids microcapsules are shown in Table 1:

[0104] Table 1 Effect of different embedding wall materials on the embedding rate of tangerine peel flavonoids microcapsules

[0105]

[0106] As shown in Table 1, plant protein and maltodextrin can effectively encapsulate tangerine peel flavonoids as encapsulation wall materials, and the encapsulation rates of microcapsules obtained by using different plant protein wall materials are as follows: sesame protein isolate> amaranth protein> lupin protein> sunflower seed protein> rapeseed protein isolate> soy protein isolate. Among them, the encapsulation rate of the wall material combination of sesame protein isolate and maltodextrin in Example 3 is the highest, reaching 93.7%.

[0107] In Examples 7-9, sesame protein isolate and maltodextrin were used as embedding wall materials, and other experimental conditions were kept unchanged. Compared with Example 3, the parameters that may affect the embedding rate were adjusted to observe their effects on the embedding effect: in Example 7, the stirring speed of the wall material and core material was increased from 700rpm to 900rpm; in Example 8, the core-wall ratio was adjusted from 1:14 to 1:8; and in Example 9, the wall material ratio was changed from 1:1 to 2:3. It can be seen that the effects of stirring speed, core-wall ratio and wall material ratio on the embedding rate are smaller than those of protein types. According to the data analysis in Table 1, the use of sesame protein isolate and maltodextrin as embedding materials has a high embedding rate and can effectively encapsulate tangerine peel flavonoids in the wall material.

[0108] In the comparative example, the embedding wall materials of sesame protein isolate and maltodextrin with the highest embedding rate were selected, and the core material was the tangerine peel flavonoid core material obtained by ultrasonic assisted extraction or ethanol hot reflux method, and the embedding rate was compared with the tangerine peel flavonoid core material obtained by embedding subcritical extraction method. The embedding rates of microcapsules obtained by different methods were as follows: subcritical extraction method > ultrasonic assisted extraction method > ethanol hot reflux method. It can be seen that the core materials obtained by different extraction methods will also affect the embedding rate.

[0109] Effect Example 2 Storage Stability of Tangerine Peel Flavonoids Microcapsules

[0110] (1) Storage stability test method

[0111] The microcapsules (1.5 g) were placed in 50 mL amber glass bottles and stored at room temperature (25 °C) for 28 days. The storage stability was monitored by measuring the total flavonoid retention every 7 days;

[0112] Total flavonoids retention rate (%) = total flavonoids content after storage / total flavonoids content before storage * 100%;

[0113] (2) Storage stability test results: The test results are shown in Table 2.

[0114] Table 2

[0115]

[0116] As can be seen from Table 2, the storage time has little effect on the tangerine peel microcapsules. As the storage time increases, the total flavonoid retention rate of the tangerine peel flavonoid microcapsules shows a downward trend, but the difference is small and the change is not significant. In summary, the storage time has little effect on the microcapsules, and the tangerine peel flavonoid microcapsules can be safely stored for one month without much significant change.

[0117] In summary, the embedding wall material of the present invention has a high embedding rate of microcapsules prepared by the inventive technology and has strong storage stability; and the microcapsule wall material is natural and non-toxic, the preparation method is simple, the cost is low, and it is suitable for large-scale production.

[0118] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing tangerine peel flavonoids microcapsules, characterized in that The steps include: (1) Preparation of core material: Using ethanol solution as extraction solvent, extracting tangerine peel powder by subcritical extraction method, concentrating the obtained extract under reduced pressure, and freeze-drying to obtain tangerine peel flavonoid freeze-dried powder; dissolving the tangerine peel flavonoid freeze-dried powder in water to obtain core material solution; (2) Preparation of wall material: dissolving maltodextrin and vegetable protein in water to obtain a wall material solution; (3) Preparation of tangerine peel flavonoids microcapsules: The core material solution obtained in step (1) and the wall material solution obtained in step (2) are mixed evenly, and vacuum freeze-dried to obtain tangerine peel flavonoids microcapsules.

2. The method for preparing tangerine peel flavonoids microcapsules according to claim 1, wherein: The consumption of the ethanol solution described in the step (1) is calculated by proportioning 20-30 mL of ethanol solution with 1 g of dried tangerine peel powder; The concentration of the ethanol solution in step (1) is 55 to 95% by volume; The extraction conditions described in step (1) are as follows: the extraction temperature is 120-160° C., and the extraction time is 30-120 min.

3. The method for preparing tangerine peel flavonoids microcapsules according to claim 1, wherein: The tangerine peel powder described in step (1) is the tangerine peel powder that can be obtained by passing through an 80-mesh sieve; The freeze-drying conditions described in step (1) are: pressure 0.5-1.5 Pa, cold trap temperature -60°C.

4. The method for preparing tangerine peel flavonoids microcapsules according to claim 1, wherein: Step (2) is as follows: maltodextrin and vegetable protein are dissolved in water respectively, and then the obtained maltodextrin solution and vegetable protein solution are mixed to obtain a wall material solution.

5. The method for preparing tangerine peel flavonoids microcapsules according to claim 4, wherein: The plant protein in step (2) is at least one of sunflower seed protein, rapeseed protein isolate, sesame protein isolate, amaranth protein, lupine protein and soy protein isolate; The concentration of the maltodextrin solution is preferably 8 to 12% by mass volume; The concentration of the vegetable protein solution is preferably 5 to 15% by mass volume; The maltodextrin solution and the plant protein solution are mixed in a mass ratio of 1:9 to 1:

9.

6. The method for preparing tangerine peel flavonoids microcapsules according to claim 1, wherein: The concentration of the core material solution in step (1) is 1 to 10% by mass; The concentration of maltodextrin in the wall material solution in step (2) is 2-10%, and the concentration of plant protein is 2-10%; The core material and the wall material of the tangerine peel flavonoids microcapsules described in step (3) are mixed in a mass ratio of 7.5-10:80-140.

7. The method for preparing tangerine peel flavonoids microcapsules according to claim 1, wherein: The mixing conditions described in step (3) are as follows: stirring speed 200-900 rpm, stirring time 10-60 min.

8. A tangerine peel flavonoids microcapsule, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the tangerine peel flavonoids microcapsules according to claim 8 in the preparation of food additives.

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